Research On Pretreatment Of The Developing And Fixing Solution

Developing and fixing solution belongs to sensitive material waste, which is NO.16HW waste according to the National Dangerous Wastes Catalogue. It is refractory industrial waste water of high concentration and toxicity. The waste water mainly produced in photography industry chemicals, printing factory, photographic studios flush department and the CT examination and the X-ray room in each large hospital. As is known to most of us, wide emission sources and small drainage areas lead to difficult collection. After extracting and purifying silver, individuals sent out wastewater without permission. According to statistics, the large amount of wastewater emission seriously harmed the ecosystem. What’s more, it cannot meet requirement as we expected after using biological methods. In this research, we studied the pretreatment methods and changes in matter between pretreatment and post treatment on the basis of the character of the wastewater, so as to provide some reference for advanced treatment of developing and fixing solution.Fenton’s reagent oxidization, aerate ferric-carbon micro-electrolysis and ozone oxidization methods were adopted in pretreatment experiment. Factors affecting treatment efficiency of the three were examined. The results are as following.For Fenton’s reagent oxidization, under the optimal conditions where H2O2to Fe2+molar ratio was8and H2O2dosage was2mol/L, the reaction time was40min and pH was3.0. Under this conditions, the CODCr removal rate reached to38.9%.For aerate ferric-carbon micro-electrolysis method, the CODCr removal rate could reach to45.62%under the optimal conditions of pH at2.5,iron to carbon weight ratio of3.0:1, reaction time for3.Oh.For ozone oxidization the optimal conditions were:reaction time of140min, pH at8.5, the ozone dosage of6mg/L, under which the CODCr removal rate reached to29.8%. After the comparison among the three methods and the changes in matter between pretreatment and post treatment of the wastewater using gas chromatography and mass spectrometry (GC-MS), we concluded that aerate ferric-carbon micro-electrolysis method was the best way to pretreat the wastewater after taking into account the cost and treatment of wastes with processes of wastes against one another.